Image sensor structure and manufacturing method thereof

ABSTRACT

An image sensor structure including a substrate, a nanowire structure, a first conductive line, a second conductive line, and a third conductive line is provided. The nanowire structure includes a first doped layer, a second doped layer, a third doped layer, and a fourth doped layer sequentially stacked on the substrate. The first doped layer and the third doped layer have a first conductive type. The second doped layer and the fourth doped layer have a second conductive type. The first conductive line is connected to a sidewall of the second doped layer. The second conductive line is connected to a sidewall of the third doped layer. The third conductive line is connected to the fourth doped layer.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Taiwan application serial no. 110113759, filed on Apr. 16, 2021. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to a semiconductor structure, and particularly relates to an image sensor structure.

Description of Related Art

A pixel structure of the current image sensor is formed by image sensing devices (for example, one image sensing device for sensing red light, two image sensing devices for sensing green light, and one image sensing device for sensing blue light) arranged horizontally. Therefore, the current image sensor has the problem of a large pixel area and an unbalanced energy proportion of red, green and blue (RGB).

SUMMARY OF THE INVENTION

The invention provides an image sensor structure and a manufacturing method thereof, which can effectively reduce the pixel area and have a balanced energy proportion of RGB.

The invention provides an image sensor structure, which includes a substrate, a nanowire structure, a first conductive line, a second conductive line, and a third conductive line is provided. The nanowire structure includes a first doped layer, a second doped layer, a third doped layer, and a fourth doped layer sequentially stacked on the substrate. The first doped layer and the third doped layer have a first conductive type. The second doped layer and the fourth doped layer have a second conductive type. The first conductive line is connected to the sidewall of the second doped layer. The second conductive line is connected to the sidewall of the third doped layer. The third conductive line is connected to the fourth doped layer.

According to an embodiment of the invention, in the image sensor structure, the first doped layer may be a portion of the substrate. The top surface of the first doped layer may be higher than the top surface of another portion of the substrate.

According to an embodiment of the invention, in the image sensor structure, the first doped layer and the second doped layer may form a first image sensing device. The second doped layer and the third doped layer may form a second image sensing device. The third doped layer and the fourth doped layer form a third image sensing device.

According to an embodiment of the invention, in the image sensor structure, the first image sensing device, the second image sensing device, and the third image sensing device may be photodiodes.

According to an embodiment of the invention, in the image sensor structure, the dopant concentration of the second doped layer may be greater than the dopant concentration of the first doped layer. The dopant concentration of the third doped layer may be greater than the dopant concentration of the second doped layer. The dopant concentration of the fourth doped layer may be greater than the dopant concentration of the third doped layer.

According to an embodiment of the invention, in the image sensor structure, the dopant concentration of the first doped layer may be 1×10¹⁵ ions/cm³ to 5×10¹⁵ ions/cm³, the dopant concentration of the second doped layer may be 1×10¹⁶ ions/cm³ to 5×10¹⁶ ions/cm³, the dopant concentration of the third doped layer may be 1×10¹⁷ ions/cm³ to 5×10¹⁷ ions/cm³, and the dopant concentration of the fourth doped layer may be 1×10¹⁸ ions/cm³ to 5×10¹⁸ ions/cm³.

According to an embodiment of the invention, in the image sensor structure, the third conductive line may be connected to the top surface of the fourth doped layer.

According to an embodiment of the invention, the image sensor structure may further include a first dielectric layer, a second dielectric layer, and a third dielectric layer. The first dielectric layer is disposed on the substrate. The first conductive line is disposed on the first dielectric layer. The second dielectric layer is disposed on the first dielectric layer and the first conductive line. The second conductive line is disposed on the second dielectric layer. The third dielectric layer is disposed on the second dielectric layer and the second conductive line.

According to an embodiment of the invention, the image sensor structure may further include a first conductive plug and a second conductive plug. The first conductive plug is connected to the first conductive line. The second conductive plug is connected to the second conductive line.

According to an embodiment of the invention, the image sensor structure may further include a fourth conductive line and a fifth conductive line. The fourth conductive line is connected to the first conductive plug. The fifth conductive line is connected to the second conductive plug.

The invention provides another image sensor structure, which includes a substrate, a nanowire structure, a first conductive line, a second conductive line, and a third conductive line is provided. The nanowire structure includes a first doped layer, a second doped layer, a third doped layer, and a fourth doped layer sequentially stacked on the substrate. The first doped layer and the third doped layer have a first conductive type. The second doped layer and the fourth doped layer have a second conductive type. The first conductive line is connected to the sidewall of the second doped layer. The cross-sectional shape of the first conductive line is L-shaped. The second conductive line is connected to the sidewall of the third doped layer. The cross-sectional shape of the second conductive line is L-shaped. The third conductive line is connected to the fourth doped layer.

The invention provides a manufacturing method of an image sensor structure, which includes the following steps. A substrate is provided. The substrate is a first doped material layer. A second doped material layer, a third doped material layer, and a fourth doped material layer are sequentially formed on the substrate. The substrate and the third doped material layer have a first conductive type. The second doped material layer and the fourth doped material layer have a second conductive type. The substrate, the second doped material layer, the third doped material layer, and the fourth doped material layer are patterned to form a nanowire structure. The nanowire structure includes a first doped layer, a second doped layer, a third doped layer, and a fourth doped layer sequentially stacked on the substrate. The first doped layer and the third doped layer have the first conductive type. The second doped layer and the fourth doped layer have the second conductive type. A first conductive line connected to the sidewall of the second doped layer is formed. A second conductive line connected to the sidewall of the third doped layer is formed. A third conductive line connected to the fourth doped layer is formed.

According to an embodiment of the invention, in the manufacturing method of the image sensor structure, the method of forming the second doped material layer, the third doped material layer, and the fourth doped material layer may include the following steps. A first epitaxial growth process is performed to form the second doped material layer on the substrate. A second epitaxial growth process is performed to form the third doped material layer on the second doped material layer. A third epitaxial growth process is performed to form the fourth doped material layer on the third doped material layer.

According to an embodiment of the invention, in the manufacturing method of the image sensor structure, the method of forming the second doped material layer, the third doped material layer, and the fourth doped material layer may include the following steps. A first ion implantation process is performed on the substrate to form the second doped material layer. After the first ion implantation process is performed, a second ion implantation process is performed on the substrate to form the third doped material layer. After the second ion implantation process is performed, a third ion implantation process is performed on the substrate to form the fourth doped material layer.

According to an embodiment of the invention, the manufacturing method of the image sensor structure may further include the following step. After the third ion implantation process is performed, a thermal process is performed on the substrate.

According to an embodiment of the invention, in the manufacturing method of the image sensor structure, the dopant concentration of the second doped layer may be greater than the dopant concentration of the first doped layer. The dopant concentration of the third doped layer may be greater than the dopant concentration of the second doped layer. The dopant concentration of the fourth doped layer may be greater than the dopant concentration of the third doped layer.

According to an embodiment of the invention, in the manufacturing method of the image sensor structure, the method of forming the first conductive line may include the following steps. A first dielectric layer is formed on the substrate, the first doped layer, and the second doped layer. The first dielectric layer exposes a portion of the sidewall of the second doped layer. A first conductive layer is conformally formed on the first dielectric layer, the second doped layer, the third doped layer, and the fourth doped layer. A first patterned photoresist layer is formed on the first conductive layer, the second doped layer, the third doped layer, and the fourth doped layer. The height of the first patterned photoresist layer is reduced. After the height of the first patterned photoresist layer is reduced, the height of the top surface of the first patterned photoresist layer may be lower than the height of the top surface of the second doped layer, and the first patterned photoresist layer may expose a portion of the first conductive layer. The portion of the first conductive layer exposed by the first patterned photoresist layer is removed to form a first conductive line.

According to an embodiment of the invention, in the manufacturing method of the image sensor structure, the method of forming the second conductive line may include the following steps. A second dielectric layer is formed on the first dielectric layer and the first conductive line. The second dielectric layer exposes a portion of the sidewall of the third doped layer. A second conductive layer is conformally formed on the second dielectric layer, the third doped layer, and the fourth doped layer. A second patterned photoresist layer is formed on the second conductive layer, the third doped layer, and the fourth doped layer. The height of the second patterned photoresist layer is reduced. After the height of the second patterned photoresist layer is reduced, the height of the top surface of the second patterned photoresist layer may be lower than the height of the top surface of the third doped layer, and the second patterned photoresist layer may expose a portion of the second conductive layer. The portion of the second conductive layer exposed by the second patterned photoresist layer is removed to form a second conductive line.

According to an embodiment of the invention, the manufacturing method of the image sensor structure may further include the following steps. A first conductive plug connected to the first conductive line is formed. A second conductive plug connected to the second conductive line is formed.

According to an embodiment of the invention, the manufacturing method of the image sensor structure may further include the following steps. A fourth conductive line connected to the first conductive plug is formed. A fifth conductive line connected to the second conductive plug is formed.

Based on the above description, in the image sensor structure and the manufacturing method according to the invention, the nanowire structure includes the first doped layer, the second doped layer, the third doped layer, and the fourth doped layer sequentially stacked on the substrate. The first doped layer and the third doped layer have the first conductive type, and the second doped layer and the fourth doped layer have the second conductive type. Thereby, the pixel of the image sensor structure can have image sensing devices that are vertically stacked and respectively used to sense red light, green light, and blue light. Therefore, the pixel area can be effectively reduced, and the energy proportion of RGB can be balanced.

In order to make the aforementioned and other objects, features and advantages of the invention comprehensible, several exemplary embodiments accompanied with figures are described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

FIG. 1A to FIG. 1R are cross-sectional views illustrating a manufacturing process of an image sensor structure according to an embodiment of the invention.

FIG. 2A to FIG. 2T are cross-sectional views illustrating a manufacturing process of an image sensor structure according to another embodiment of the invention.

DESCRIPTION OF THE EMBODIMENTS

FIG. 1A to FIG. 1R are cross-sectional views illustrating a manufacturing process of an image sensor structure according to an embodiment of the invention.

Referring to FIG. 1A, a substrate 100 is provided. The substrate 100 is a doped material layer. In some embodiments, the substrate 100 may be a doped semiconductor substrate, such as a doped single crystal silicon substrate. The substrate 100 has the first conductive type (e.g., P-type). Hereinafter, the first conductive type and the second conductive type may be different conductive types. The first conductive type and the second conductive type may be one and the other of the P-type and the N-type, respectively. In the present embodiment, the first conductive type is, for example, P-type, and the second conductive type is, for example, N-type, but the invention is not limited thereto. In other embodiments, the first conductive type may be N-type, and the second conductive type may be P-type. In the present embodiment, the conductive type of the substrate 100 is, for example, P-type, and the dopant of the substrate 100 may include boron (B).

A doped material layer 102, a doped material layer 104, and a doped material layer 106 are sequentially formed on the substrate 100. The doped material layer 102 and the doped material layer 106 have the second conductive type (e.g., N-type). The doped material layer 104 has the first conductive type (e.g., P-type). The dopant concentration (e.g., N-type dopant concentration) of the doped material layer 102 may be greater than the dopant concentration (e.g., P-type dopant concentration) of the substrate 100. The dopant concentration (e.g., P-type dopant concentration) of the doped material layer 104 may be greater than the dopant concentration (e.g., N-type dopant concentration) of the doped material layer 102. The dopant concentration (e.g., N-type dopant concentration) of the doped material layer 106 may be greater than the dopant concentration (e.g., P-type dopant concentration) of the doped material layer 104. For example, the dopant concentration of the substrate 100 may be 1×10¹⁵ ions/cm³ to 5×10¹⁵ ions/cm³, the dopant concentration of the doped material layer 102 may be 1×10¹⁶ ions/cm³ to 5×10¹⁶ ions/cm³, the dopant concentration of the doped material layer 104 may be 1×10¹⁷ ions/cm³ to 5×10¹⁷ ions/cm³, and the dopant concentration of the doped material layer 106 may be 1×10¹⁸ ions/cm³ to 5×10¹⁸ ions/cm³.

In some embodiments, the method of forming the doped material layer 102, the doped material layer 104, and the doped material layer 106 may include the following steps. A first epitaxial growth process is performed to form the doped material layer 102 on the substrate 100. A second epitaxial growth process is performed to form the doped material layer 104 on the doped material layer 102. A third epitaxial growth process is performed to form the doped material layer 106 on the doped material layer 104. The first epitaxial growth process, the second epitaxial growth process, and the third epitaxial growth process may be epitaxial growth processes with in-situ doping.

In some embodiments, in the case that the N-type doped material layer 102 is formed by the first epitaxial growth process, the N-type dopant used in the first epitaxial growth process may include arsenic (As), antimony (Sb), bismuth (Bi), or tellurium (Te). The thickness of the doped material layer 102 is, for example, 1 μm to 2 μm. In some embodiments, in the case that the P-type doped material layer 104 is formed by the second epitaxial growth process, the P-type dopant used in the second epitaxial growth process may include boron. In addition, the dopant used in the second epitaxial growth process may further include carbon, thereby effectively inhibiting the boron dopants in the doped material layer 104 from diffusing into the adjacent layers. The concentration of the boron dopant in the doped material layer 104 may be 1×10¹⁷ ions/cm³ to 5×10¹⁷ ions/cm³. The thickness of the doped material layer 104 is, for example, 0.3 μm to 0.6 μm. In some embodiments, in the case that the N-type doped material layer 106 is formed by the third epitaxial growth process, the N-type dopant used in the third epitaxial growth process may include arsenic, antimony, bismuth, or tellurium. The thickness of the doped material layer 106 is, for example, 0.15 μm to 0.35 μm.

In other embodiments, the method of forming the doped material layer 102, the doped material layer 104, and the doped material layer 106 may include the following steps. A first ion implantation process is performed on the substrate 100 to form the doped material layer 102. After the first ion implantation process is performed, a second ion implantation process is performed on the substrate 100 to form the doped material layer 104. After the second ion implantation process is performed, a third ion implantation process is performed on the substrate 100 to form the doped material layer 106.

In some embodiments, in the case that the N-type doped material layer 102 is formed by the first ion implantation process, the N-type dopant used in the first ion implantation process may include phosphorus (P) or arsenic. In some embodiments, in the case that the P-type doped material layer 104 is formed by the second ion implantation process, the P-type dopant used in the second ion implantation process may include boron, boron difluoride (BF₂), or indium (In). In addition, in the case that the P-type dopant used in the second ion implantation process is boron or boron difluoride (BF₂), the dopant used in the second ion implantation process may further include carbon, thereby effectively inhibiting the boron dopants in the doped material layer 104 from diffusing into the adjacent layers. The concentration of the boron dopant in the doped material layer 104 may be 1×10¹⁷ ions/cm³ to 5×10¹⁷ ions/cm³. In some embodiments, in the case that the N-type doped material layer 106 is formed by the third ion implantation process, the N-type dopant used in the third ion implantation process may include phosphorus, arsenic, antimony, or tellurium. In some embodiments, after the third ion implantation process is performed, a thermal process may be performed to the substrate 100, thereby repairing defects generated by the ion implantation process.

A hard mask material layer 108 may be formed on the doped material layer 106. The material of the hard mask material layer 108 is, for example, silicon oxide, silicon nitride, or a combination thereof. The method of forming the hard mask material layer 108 is, for example, a chemical vapor deposition (CVD) method.

Referring to FIG. 1B, the substrate 100, the doped material layer 102, the doped material layer 104, and the doped material layer 106 are patterned to form a nanowire structure 110. The nanowire structure 110 includes a doped layer 100 a, a doped layer 102 a, a doped layer 104 a, and a doped layer 106 a sequentially stacked on the substrate 100. The doped layer 100 a and the doped layer 104 a have the first conductive type (e.g., P-type). The doped layer 102 a and the doped layer 106 a have the second conductive type (e.g., N-type). The doped layer 100 a, the doped layer 102 a, the doped layer 104 a, and the doped layer 106 a may be nanowires. Furthermore, the hard mask material layer 108 may be patterned to form a hard mask layer 108 a on the doped layer 106 a. For example, the hard mask material layer 108, the doped material layer 106, the doped material layer 104, the doped material layer 102, and the substrate 100 may be patterned by a lithography process and an etching process to form the doped layer 100 a, the doped layer 102 a, the doped layer 104 a, the doped layer 106 a, and the hard mask layer 108 a sequentially stacked on the substrate 100.

Referring to FIG. 1C, a liner material layer 112 may be conformally formed on the substrate 100, the nanowire structure 110, and the hard mask layer 108 a. The material of the liner material layer 112 is, for example, silicon oxide. The method of forming the liner material layer 112 is, for example, a thermal oxidation method, a CVD method, or an atomic layer deposition (ALD) method.

A dielectric material layer 114 may be formed on the liner material layer 112. The material of the dielectric material layer 114 is, for example, silicon nitride (SiN), silicon carbonitride (SiCN), silicon oxynitride (SiON), or a combination thereof. The method of forming the dielectric material layer 114 is, for example, a CVD method, a physical vapor deposition (PVD) method, or an ALD method.

Referring to FIG. 1D, a portion of the dielectric material layer 114 and a portion of the liner material layer 112 may be removed to expose the top surface of the hard mask layer 108 a. The method of removing a portion of the dielectric material layer 114 and a portion of the liner material layer 112 is, for example, a chemical mechanical polishing (CMP) method. Moreover, after a portion of the dielectric material layer 114 and a portion of the liner material layer 112 are removed by the CMP method, the top surface of the dielectric material layer 114, the top surface of the liner material layer 112, and the top surface of the hard mask layer 108 a may be flush with each other.

Referring to FIG. 1E, a portion of the dielectric material layer 114 and a portion of the liner material layer 112 may be removed, thereby forming a dielectric layer 114 a and a liner layer 112 a on the substrate 100, the doped layer 100 a, and the doped layer 102 a. The dielectric layer 114 a may be located on the liner layer 112 a. The liner layer 112 a may be in direct contact with the substrate 100, the doped layer 100 a, and the doped layer 102 a. The dielectric layer 114 a and the liner layer 112 a may expose a portion of the sidewall of the doped layer 102 a. In some embodiments, a portion of the dielectric material layer 114 may be removed, and then a portion of the liner material layer 112 may be removed, but the invention is not limited thereto. The method of removing a portion of the dielectric material layer 114 is, for example, an etching method. The method of removing a portion of the liner material layer 112 is, for example, an etching method.

Referring to FIG. 1F, a conductive layer 116 may be conformally formed on the dielectric layer 114 a, the doped layer 102 a, the doped layer 104 a, the doped layer 106 a, and the hard mask layer 108 a. The material of the conductive layer 116 is, for example, tungsten (W), aluminum (Al), titanium nitride (TiN), tantalum nitride (TaN), titanium carbide (TiC), titanium aluminum (TiAl), titanium aluminum nitride (TiAlN), titanium carbon nitride (TiCN) or doped polysilicon. The method of forming the conductive layer 116 is, for example, a CVD method or an ALD method. In some embodiments, an etch stop layer (not shown) may be conformally formed on the conductive layer 116, and the description thereof is omitted here.

A patterned photoresist layer 118 may be formed on the conductive layer 116, the doped layer 102 a, the doped layer 104 a, the doped layer 106 a, and the hard mask layer 108 a. The patterned photoresist layer 118 may be formed by a lithography process.

Referring to FIG. 1G the height of the patterned photoresist layer 118 may be reduced. After the height of the patterned photoresist layer 118 is reduced, the height of the top surface of the patterned photoresist layer 118 may be lower than the height of the top surface of the doped layer 102 a, and the patterned photoresist layer 118 may expose a portion of the conductive layer 116. The method of reducing the height of the patterned photoresist layer 118 is, for example, an etching method.

Referring to FIG. 1H, the portion of the conductive layer 116 exposed by the patterned photoresist layer 118 may be removed to form a conductive line 116 a. Thereby, a conductive line 116 a connected to the sidewall of the doped layer 102 a may be formed. The conductive line 116 a may be electrically connected to the doped layer 102 a. In some embodiments, the conductive line 116 a may be in direct contact with the doped layer 102 a. The method of removing the portion of the conductive layer 116 is, for example, an etching method.

The patterned photoresist layer 118 may be removed. The method of removing the patterned photoresist layer 118 is, for example, a dry stripping method or a wet stripping method.

Referring to FIG. 1I, a liner material layer 120 may be conformally formed on the dielectric layer 114 a, the conductive line 116 a, the doped layer 102 a, the doped layer 104 a, the doped layer 106 a, and the hard mask layer 108 a. The material of the liner material layer 120 is, for example, silicon oxide. The method of forming the liner material layer 120 is, for example, a CVD method or an ALD method.

A dielectric material layer 122 may be formed on the liner material layer 120. The material of the dielectric material layer 122 is, for example, silicon nitride, silicon carbonitride, silicon oxynitride, or a combination thereof. The method of forming the dielectric material layer 122 is, for example, a CVD method, a PVD method, or an ALD method.

Referring to FIG. 1J, a portion of the dielectric material layer 122 and a portion of the liner material layer 120 may be removed. The method of removing a portion of the dielectric material layer 122 and a portion of the liner material layer 120 is, for example, a CMP method. In addition, after a portion of the dielectric material layer 122 and a portion of the liner material layer 120 are removed by the CMP method, the top surface of the dielectric material layer 122, the top surface of the liner material layer 120, and the top surface of the hard mask layer 108 a may be flush with each other.

Referring to FIG. 1K, a portion of the dielectric material layer 122 and a portion of the liner material layer 120 may be removed, thereby forming a dielectric layer 122 a and a liner layer 120 a on the dielectric layer 114 a and the conductive line 116 a. The dielectric layer 122 a may be located on the liner layer 120 a. The liner layer 120 a may be in direct contact with the dielectric layer 114 a, the conductive line 116 a, the doped layer 102 a, and the doped layer 104 a. The dielectric layer 122 a and the liner layer 120 a expose a portion of the sidewall of the doped layer 104 a. In some embodiments, a portion of the dielectric material layer 122 may be removed, and then a portion of the liner material layer 120 may be removed, but the invention is not limited thereto. The method of removing a portion of the dielectric material layer 122 is, for example, an etching method. The method of removing a portion of the liner material layer 120 is, for example, an etching method.

Referring to FIG. 1L, a conductive layer 124 may be conformally formed on the dielectric layer 122 a, the doped layer 104 a, the doped layer 106 a, and the hard mask layer 108 a. The material of the conductive layer 124 is, for example, tungsten, aluminum, titanium nitride, tantalum nitride, titanium carbide, titanium aluminum, titanium aluminum nitride, titanium carbon nitride, or doped polysilicon. The method of forming the conductive layer 124 is, for example, a CVD method or an ALD method. In some embodiments, an etch stop layer (not shown) may be conformally formed on the conductive layer 124, and the description thereof is omitted here.

A patterned photoresist layer 126 may be formed on the conductive layer 124, the doped layer 104 a, the doped layer 106 a, and the hard mask layer 108 a. The patterned photoresist layer 126 may be formed by a lithography process.

Referring to FIG. 1M, the height of the patterned photoresist layer 126 may be reduced. After the height of the patterned photoresist layer 126 is reduced, the height of the top surface of the patterned photoresist layer 126 may be lower than the height of the top surface of the doped layer 104 a, and the patterned photoresist layer 126 may expose a portion of the conductive layer 124. The method of reducing the height of the patterned photoresist layer 126 is, for example, an etching method.

Referring to FIG. 1N, the portion of the conductive layer 124 exposed by the patterned photoresist layer 126 may be removed to form a conductive line 124 a. Thereby, a conductive line 124 a connected to the sidewall of the doped layer 104 a may be formed. The conductive line 124 a may be electrically connected to the doped layer 104 a. In some embodiments, the conductive line 124 a may be in direct contact with the doped layer 104 a. The method of removing the portion of the conductive layer 124 is, for example, an etching method.

The patterned photoresist layer 126 may be removed. The method of removing the patterned photoresist layer 126 is, for example, a dry stripping method or a wet stripping method.

Referring to FIG. 1O, a liner material layer 128 may be conformally formed on the dielectric layer 122 a, the conductive line 124 a, the doped layer 104 a, the doped layer 106 a, and the hard mask layer 108 a. The material of the liner material layer 128 is, for example, silicon oxide. The method of forming the liner material layer 128 is, for example, a CVD method or an ALD method.

A dielectric material layer 130 may be formed on the liner material layer 128. The material of the dielectric material layer 130 is, for example, silicon nitride, silicon carbonitride, silicon oxynitride, or a combination thereof. The method of forming the dielectric material layer 130 is, for example, a CVD method, a PVD method, or an ALD method.

Referring to FIG. 1P, a portion of the dielectric material layer 130, a portion of the liner material layer 128, and the hard mask layer 108 a may be removed, thereby exposing the top surface of the doped layer 106 a and forming a dielectric layer 130 a and a liner layer 128 a on the dielectric layer 122 a and the conductive line 124 a. The dielectric layer 130 a may be located on the liner layer 128 a. The liner layer 128 a may be in direct contact with the dielectric layer 122 a, the conductive line 124 a, the doped layer 104 a, and the doped layer 106 a. In some embodiments, a portion of the doped layer 106 a may be removed. The method of removing a portion of the dielectric material layer 130, a portion of the liner material layer 128, the hard mask layer 108 a, and a portion of the doped layer 106 a is, for example, a CMP method.

Referring to FIG. 1Q, an opening OP1 exposing the conductive line 116 a may be formed in the dielectric layer 130 a, the liner layer 128 a, the dielectric layer 122 a, and the liner layer 120 a, and an opening OP2 exposing the conductive line 124 a may be formed in the dielectric layer 130 a and the liner layer 128 a. The method of forming the opening OP1 is, for example, removing a portion of the dielectric layer 130 a, a portion of the liner layer 128 a, a portion of the dielectric layer 122 a, and a portion of the liner layer 120 a by a lithography process and an etching process. In addition, the method of forming the opening OP2 is, for example, removing a portion of the dielectric layer 130 a and a portion of the liner layer 128 a by a lithography process and an etching process.

Referring to FIG. 1R, a conductive plug 132 and a conductive plug 134 may be respectively formed in the opening OP1 and the opening OP2. Thereby, the conductive plug 132 connected to the conductive line 116 a may be formed, and the conductive plug 134 connected to the conductive line 124 a may be formed. The material of the conductive plug 132 and the conductive plug 134 is, for example, tungsten. The conductive plug 132 and the conductive plug 134 may be electrically connected to the conductive line 116 a and the conductive line 124 a, respectively. In some embodiments, the conductive plug 132 may be in direct contact with the conductive line 116 a, and the conductive plug 134 may be in direct contact with the conductive line 124 a. The method of forming the conductive plug 132 and the conductive plug 134 is, for example, forming a conductive layer (not shown) filling the opening OP1 and the opening OP2, and then removing the conductive layer located outside the opening OP1 and the opening OP2 by a CMP method.

A conductive line 136 connected to the doped layer 106 a is formed. In addition, a conductive line 138 connected to the conductive plug 132 may be formed. Furthermore, a conductive line 140 connected to the conductive plug 134 may be formed. The conductive line 136, the conductive line 138, and the conductive line 140 may be located on the same plane, thereby facilitating the integration with the back end of line (BEOL) process. The conductive line 136, the conductive line 138, and the conductive line 140 may be electrically connected to the doped layer 106 a, the conductive plug 132, and the conductive plug 134, respectively. In some embodiments, the conductive line 136 may be in direct contact with the doped layer 106 a, the conductive line 138 may be in direct contact with the conductive plug 132, and the conductive line 140 may be in direct contact with the conductive plug 134. The material of the conductive line 136, the conductive line 138, and the conductive line 140 is, for example, aluminum, tungsten, or titanium. The method of forming the conductive line 136, the conductive line 138, and the conductive line 140 is, for example, forming a conductive layer (not shown) by a deposition process, and then patterning the conductive layer by a lithography process and an etching process.

Hereinafter, the image sensor structure 10 of the above embodiment will be described with reference to FIG. 1R. In addition, although the method for forming the image sensor structure 10 is described by taking the above method as an example, the invention is not limited thereto.

Referring to FIG. 1R, the image sensor structure 10 includes a substrate 100, a nanowire structure 110, a conductive line 116 a, a conductive line 124 a, and a conductive line 136. The nanowire structure 110 includes a doped layer 100 a, a doped layer 102 a, a doped layer 104 a, and a doped layer 106 a sequentially stacked on the substrate 100. The doped layer 100 a and the doped layer 104 a have the first conductive type (e.g., P-type). The doped layer 102 a and the doped layer 106 a have the second conductive type (e.g., N-type). The doped layer 100 a and the doped layer 102 a may form an image sensing device 142. The doped layer 102 a and the doped layer 104 a may form an image sensing device 144. The doped layer 104 a and the doped layer 106 a may form an image sensing device 146. For example, the image sensing device 142 may be an image sensing device for sensing red light, the image sensing device 144 may be an image sensing device for sensing green light, and the image sensing device 146 may be an image sensing device for sensing blue light. The image sensing device 142, the image sensing device 144, and the image sensing device 146 may be photodiodes. The doped layer 100 a may be a portion of the substrate 100. The top surface of the doped layer 100 a may be higher than the top surface of another portion of the substrate 100.

The dopant concentration (e.g., N-type dopant concentration) of the doped layer 102 a may be greater than the dopant concentration (e.g., P-type dopant concentration) of the doped layer 100 a. The dopant concentration (e.g., P-type dopant concentration) of the doped layer 104 a may be greater than the dopant concentration (e.g., N-type dopant concentration) of the doped layer 102 a. The dopant concentration (e.g., N-type dopant concentration) of the doped layer 106 a may be greater than the dopant concentration (e.g., P-type dopant concentration) of the doped layer 104 a. For example, the dopant concentration of the doped layer 100 a may be 1×10¹⁵ ions/cm³ to 5×10¹⁵ ions/cm³, the dopant concentration of the doped layer 102 a may be 1×10¹⁶ ions/cm³ to 5×10¹⁶ ions/cm³, the dopant concentration of the doped layer 104 a may be 1×10¹⁷ ions/cm³ to 5×10¹⁷ ions/cm³, and the dopant concentration of the doped layer 106 a may be 1×10¹⁸ ions/cm³ to 5×10¹⁸ ions/cm³.

The conductive line 116 a is connected to the sidewall of the doped layer 102 a. In some embodiments, the cross-sectional shape of the conductive line 116 a may be L-shaped. The conductive line 124 a is connected to the sidewall of the doped layer 104 a. In some embodiments, the cross-sectional shape of the conductive line 124 a may be L-shaped. The conductive line 136 is connected to the doped layer 106 a. The conductive line 136 may be connected to the top surface of the doped layer 106 a.

The image sensor structure 10 may further include at least one of a dielectric layer 114 a, a dielectric layer 122 a, a dielectric layer 130 a, a liner layer 112 a, a liner layer 120 a, and a liner layer 128 a. The dielectric layer 114 a is disposed on the substrate 100. The conductive line 116 a is disposed on the dielectric layer 114 a. The liner layer 112 a is disposed between the dielectric layer 114 a and the substrate 100. The dielectric layer 122 a is disposed on the dielectric layer 114 a and the conductive line 116 a. The conductive line 124 a is disposed on the dielectric layer 122 a. The liner layer 120 a is disposed between the dielectric layer 122 a and the dielectric layer 114 a. The dielectric layer 130 a is disposed on the dielectric layer 122 a and the conductive line 124 a. The liner layer 128 a is disposed between the dielectric layer 130 a and the dielectric layer 122 a.

The image sensor structure 10 may further include at least one of a conductive plug 132, a conductive plug 134, a conductive line 138, and a conductive line 140. The conductive plug 132 is connected to the conductive line 116 a. The conductive plug 134 is connected to the conductive line 124 a. The conductive line 138 is connected to the conductive plug 132. The conductive line 140 is connected to the conductive plug 134.

In addition, the material, the arrangement, the forming method, and the effect of each component in the image sensor structure 10 have been described in detail in the above embodiments and are not repeated herein.

Based on the above embodiment, in the image sensor structure 10 and the manufacturing method thereof, the nanowire structure 110 includes the doped layer 100 a, the doped layer 102 a, the doped layer 104 a, and the doped layer 106 a sequentially stacked on the substrate 100. The doped layer 100 a and the doped layer 104 a have the first conductive type, and the doped layer 102 a and the doped layer 106 a have the second conductive type. In this way, the pixel of the image sensor structure 10 can have the image sensing device 142, the image sensing device 144, and the image sensing device 146 that are vertically stacked and respectively used to sense red light, green light, and blue light, thereby effectively reducing the pixel area. In addition, since the image sensing device 142, the image sensing device 144, and the image sensing device 146 may have approximately the same top view area, the image sensor structure 10 can have a balanced energy proportion of RGB. Furthermore, the manufacturing process of the image sensor structure 10 can be integrated with the manufacturing process of the complementary metal oxide semiconductor (CMOS). Moreover, two adjacent pixels in the image sensor structure 10 can be well isolated. On the other hand, the image sensor structure 10 does not need color filters, thereby reducing the manufacturing cost and the process complexity.

FIG. 2A to FIG. 2T are cross-sectional views illustrating a manufacturing process of an image sensor structure according to another embodiment of the invention.

Referring to FIG. 2A, a substrate 200 is provided. The substrate 200 is a doped material layer. In some embodiments, the substrate 200 may be a doped semiconductor substrate, such as a doped single crystal silicon substrate. The substrate 200 has the first conductive type (e.g., P-type). Hereinafter, the first conductive type and the second conductive type may be different conductive types. The first conductive type and the second conductive type may be one and the other of the P-type and the N-type, respectively. In the present embodiment, the first conductive type is, for example, P-type, and the second conductive type is, for example, N-type, but the invention is not limited thereto. In other embodiments, the first conductive type may be N-type, and the second conductive type may be P-type. In the present embodiment, the conductive type of the substrate 200 is, for example, P-type, and the dopant of the substrate 200 may include boron.

A doped material layer 202, a doped material layer 204, and a doped material layer 206 are sequentially formed on the substrate 200. The doped material layer 202 and the doped material layer 206 have the second conductive type (e.g., N-type). The doped material layer 204 has the first conductive type (e.g., P-type). The dopant concentration (e.g., N-type dopant concentration) of the doped material layer 202 may be greater than the dopant concentration (e.g., P-type dopant concentration) of the substrate 200. The dopant concentration (e.g., P-type dopant concentration) of the doped material layer 204 may be greater than the dopant concentration (e.g., N-type dopant concentration) of the doped material layer 202. The dopant concentration (e.g., N-type dopant concentration) of the doped material layer 206 may be greater than the dopant concentration (e.g., P-type dopant concentration) of the doped material layer 204. For example, the dopant concentration of the substrate 200 may be 1×10¹⁵ ions/cm³ to 5×10¹⁵ ions/cm³, the dopant concentration of the doped material layer 202 may be 1×10¹⁶ ions/cm³ to 5×10¹⁶ ions/cm³, the dopant concentration of the doped material layer 204 may be 1×10¹⁷ ions/cm³ to 5×10¹⁷ ions/cm³, and the dopant concentration of the doped material layer 206 may be 1×10¹⁸ ions/cm³ to 5×10¹⁸ ions/cm³.

In some embodiments, the method of forming the doped material layer 202, the doped material layer 204, and the doped material layer 206 may include the following steps. A first epitaxial growth process is performed to form the doped material layer 202 on the substrate 200. A second epitaxial growth process is performed to form the doped material layer 204 on the doped material layer 202. A third epitaxial growth process is performed to form the doped material layer 206 on the doped material layer 204. The first epitaxial growth process, the second epitaxial growth process, and the third epitaxial growth process may be epitaxial growth processes with in-situ doping.

In some embodiments, in the case that the N-type doped material layer 202 is formed by the first epitaxial growth process, the N-type dopant used in the first epitaxial growth process may include arsenic, antimony, bismuth, or tellurium. The thickness of the doped material layer 202 is, for example, 1 μm to 2 μm. In some embodiments, in the case that the P-type doped material layer 204 is formed by the second epitaxial growth process, the P-type dopant used in the second epitaxial growth process may include boron. In addition, the dopant used in the second epitaxial growth process may further include carbon, thereby effectively inhibiting the boron dopants in the doped material layer 204 from diffusing into the adjacent layers. The concentration of the boron dopant in the doped material layer 204 may be 1×10¹⁷ ions/cm³ to 5×10¹⁷ ions/cm³. The thickness of the doped material layer 204 is, for example, 0.3 μm to 0.6 μm. In some embodiments, in the case that the N-type doped material layer 206 is formed by the third epitaxial growth process, the N-type dopant used in the third epitaxial growth process may include arsenic, antimony, bismuth, or tellurium. The thickness of the doped material layer 206 is, for example, 0.15 μm to 0.35 μm.

In other embodiments, the method of forming the doped material layer 202, the doped material layer 204, and the doped material layer 206 may include the following steps. A first ion implantation process is performed on the substrate 200 to form the doped material layer 202. After the first ion implantation process is performed, a second ion implantation process is performed on the substrate 200 to form the doped material layer 204. After the second ion implantation process is performed, a third ion implantation process is performed on the substrate 200 to form the doped material layer 206.

In some embodiments, in the case that the N-type doped material layer 202 is formed by the first ion implantation process, the N-type dopant used in the first ion implantation process may include phosphorus or arsenic. In some embodiments, in the case that the P-type doped material layer 204 is formed by the second ion implantation process, the P-type dopant used in the second ion implantation process may include boron, boron difluoride, or indium (In). In addition, in the case that the P-type dopant used in the second ion implantation process is boron or boron difluoride (BF₂), the dopant used in the second ion implantation process may further include carbon, thereby effectively inhibiting the boron dopants in the doped material layer 204 from diffusing into the adjacent layers. The concentration of the boron dopant in the doped material layer 204 may be 1×10¹⁷ ions/cm³ to 5×10¹⁷ ions/cm³. In some embodiments, in the case that the N-type doped material layer 206 is formed by the third ion implantation process, the N-type dopant used in the third ion implantation process may include phosphorus, arsenic, antimony, or tellurium. In some embodiments, after the third ion implantation process is performed, a thermal process may be performed to the substrate 200, thereby repairing defects generated by the ion implantation process.

A hard mask material layer 208 may be formed on the doped material layer 206. The material of the hard mask material layer 208 is, for example, silicon oxide, silicon nitride, or a combination thereof. The method of forming the hard mask material layer 208 is, for example, a CVD method.

Referring to FIG. 2B, the substrate 200, the doped material layer 202, the doped material layer 204, and the doped material layer 206 are patterned to form a nanowire structure 210. The nanowire structure 210 includes a doped layer 200 a, a doped layer 202 a, a doped layer 204 a, and a doped layer 206 a sequentially stacked on the substrate 200. The doped layer 200 a and the doped layer 204 a have the first conductive type (e.g., P-type). The doped layer 202 a and the doped layer 206 a have the second conductive type (e.g., N-type). The doped layer 200 a, the doped layer 202 a, the doped layer 204 a, and the doped layer 206 a may be nanowires. Furthermore, the hard mask material layer 208 may be patterned to form a hard mask layer 208 a on the doped layer 206 a. For example, the hard mask material layer 208, the doped material layer 206, the doped material layer 204, the doped material layer 202, and the substrate 200 may be patterned by a lithography process and an etching process to form the doped layer 200 a, the doped layer 202 a, the doped layer 204 a, the doped layer 206 a, and the hard mask layer 208 a sequentially stacked on the substrate 200.

Referring to FIG. 2C, a liner material layer 212 may be conformally formed on the substrate 200, the nanowire structure 210, and the hard mask layer 208 a. The material of the liner material layer 212 is, for example, silicon oxide. The method of forming the liner material layer 212 is, for example, a thermal oxidation method, a CVD method, or an ALD method.

A dielectric material layer 214 may be formed on the liner material layer 212. The material of the dielectric material layer 214 is, for example, silicon nitride, silicon carbonitride, silicon oxynitride, or a combination thereof. The method of forming the dielectric material layer 214 is, for example, a CVD method or an ALD method.

A photoresist layer 216 may be formed on the dielectric material layer 214. The method of forming the photoresist layer 216 is, for example, a spin coating method.

Referring to FIG. 2D, a portion of the photoresist layer 216 and a portion of the dielectric material layer 214 may be removed, thereby forming a photoresist layer 216 a and a dielectric layer 214 a. In some embodiments, a portion of the photoresist layer 216 may be removed, and then a portion of the dielectric material layer 214 may be removed, but the invention is not limited thereto. The method of removing a portion of the photoresist layer 216 is, for example, an etching method. The method of removing a portion of the dielectric material layer 214 is, for example, an etching method.

Referring to FIG. 2E, a portion of the dielectric layer 214 a may be removed, so that the top surface of the dielectric layer 214 a may be lower than the top surface of the photoresist layer 216 a. The method of removing a portion of the dielectric layer 214 a is, for example, an etching method.

Referring to FIG. 2F, the photoresist layer 216 a may be removed. The method of removing the photoresist layer 216 a is, for example, a dry stripping method or a wet stripping method.

A portion of the liner material layer 212 may be removed to form a liner layer 212 a. By the above method, the dielectric layer 214 a and the liner layer 212 a may be formed on the substrate 200, the doped layer 200 a, and the doped layer 202 a. The dielectric layer 214 a may be located on the liner layer 212 a. The liner layer 212 a may be in direct contact with the substrate 200, the doped layer 200 a, and the doped layer 202 a. The dielectric layer 214 a and the liner layer 212 a may expose a portion of the sidewall of the doped layer 202 a. The method of removing a portion of the liner material layer 212 is, for example, an etching method.

Referring to FIG. 2Q a conductive layer 218 may be conformally formed on the dielectric layer 214 a, the doped layer 202 a, the doped layer 204 a, the doped layer 206 a, and the hard mask layer 208 a. The material of the conductive layer 218 is, for example, tungsten, aluminum, titanium nitride, tantalum nitride, titanium carbide, titanium aluminum, titanium aluminum nitride, titanium carbon nitride, or doped polysilicon. The method of forming the conductive layer 218 is, for example, a CVD method or an ALD method. In some embodiments, an etch stop layer (not shown) may be conformally formed on the conductive layer 218, and the description thereof is omitted here.

A patterned photoresist layer 220 may be formed on the conductive layer 218, the doped layer 202 a, the doped layer 204 a, the doped layer 206 a, and the hard mask layer 208 a. The patterned photoresist layer 220 may be formed by a lithography process.

Referring to FIG. 2H, the height of the patterned photoresist layer 220 may be reduced. After the height of the patterned photoresist layer 220 is reduced, the height of the top surface of the patterned photoresist layer 220 may be lower than the height of the top surface of the doped layer 202 a, and the patterned photoresist layer 220 may expose a portion of the conductive layer 218. The method of reducing the height of the patterned photoresist layer 220 is, for example, an etching method.

Referring to FIG. 2I, the portion of the conductive layer 218 exposed by the patterned photoresist layer 220 may be removed to form a conductive line 218 a. Thereby, a conductive line 218 a connected to the sidewall of the doped layer 202 a may be formed. The conductive line 218 a may be electrically connected to the doped layer 202 a. In some embodiments, the conductive line 218 a may be in direct contact with the doped layer 202 a. The method of removing the portion of the conductive layer 218 is, for example, an etching method.

Then, the patterned photoresist layer 220 may be removed. The method of removing the patterned photoresist layer 220 is, for example, a dry stripping method or a wet stripping method.

Referring to FIG. 2J, a liner material layer 222 may be conformally formed on the dielectric layer 214 a, the conductive line 218 a, the doped layer 202 a, the doped layer 204 a, the doped layer 206 a, and the hard mask layer 208 a. The material of the liner material layer 222 is, for example, silicon oxide. The method of forming the liner material layer 222 is, for example, a CVD method or an ALD method.

A dielectric material layer 224 may be formed on the liner material layer 222. The material of the dielectric material layer 224 is, for example, silicon nitride, silicon carbonitride, silicon oxynitride, or a combination thereof. The method of forming the dielectric material layer 224 is, for example, a CVD method or an ALD method.

A photoresist layer 226 may be formed on the dielectric material layer 224. The method of forming the photoresist layer 226 is, for example, a spin coating method.

Referring to FIG. 2K, a portion of the photoresist layer 226 and a portion of the dielectric material layer 224 may be removed, thereby forming a photoresist layer 226 a and a dielectric layer 224 a. In some embodiments, a portion of the photoresist layer 226 may be removed, and then a portion of the dielectric material layer 224 may be removed, but the invention is not limited thereto. The method of removing a portion of the photoresist layer 226 is, for example, an etching method. The method of removing a portion of the dielectric material layer 224 is, for example, an etching method.

Referring to FIG. 2L, a portion of the dielectric layer 224 a may be removed, so that the top surface of the dielectric layer 224 a may be lower than the top surface of the photoresist layer 226 a. The method of removing a portion of the dielectric layer 224 a is, for example, an etching method.

Referring to FIG. 2M, the photoresist layer 226 a may be removed. The method of removing the photoresist layer 226 a is, for example, a dry stripping method or a wet stripping method.

A portion of the liner material layer 222 may be removed to form a liner layer 222 a. By the above method, the dielectric layer 224 a and the liner layer 222 a may be formed on the dielectric layer 214 a and the conductive line 218 a. The dielectric layer 224 a may be located on the liner layer 222 a. The liner layer 222 a may be in direct contact with the dielectric layer 214 a, the conductive line 218 a, the doped layer 202 a, and the doped layer 204 a. The dielectric layer 224 a and the liner layer 222 a expose a portion of the sidewall of the doped layer 204 a. The method of removing a portion of the liner material layer 222 is, for example, an etching method.

Referring to FIG. 2N, a conductive layer 228 may be conformally formed on the dielectric layer 224 a, the doped layer 204 a, the doped layer 206 a, and the hard mask layer 208 a. The material of the conductive layer 228 is, for example, tungsten, aluminum, titanium nitride, tantalum nitride, titanium carbide, titanium aluminum, titanium aluminum nitride, titanium carbon nitride, or doped polysilicon. The method of forming the conductive layer 228 is, for example, a CVD method or an ALD method. In some embodiments, an etch stop layer (not shown) may be conformally formed on the conductive layer 228, and the description thereof is omitted here.

A patterned photoresist layer 230 may be formed on the conductive layer 228, the doped layer 204 a, the doped layer 206 a, and the hard mask layer 208 a. The patterned photoresist layer 230 may be formed by a lithography process.

Referring to FIG. 2O, the height of the patterned photoresist layer 230 may be reduced. After the height of the patterned photoresist layer 230 is reduced, the height of the top surface of the patterned photoresist layer 230 may be lower than the height of the top surface of the doped layer 204 a, and the patterned photoresist layer 230 may expose a portion of the conductive layer 228. The method of reducing the height of the patterned photoresist layer 230 is, for example, an etching method.

Referring to FIG. 2P, the portion of the conductive layer 228 exposed by the patterned photoresist layer 230 may be removed to form a conductive line 228 a. Thereby, a conductive line 228 a connected to the sidewall of the doped layer 204 a may be formed. The conductive line 228 a may be electrically connected to the doped layer 204 a. In some embodiments, the conductive line 228 a may be in direct contact with the doped layer 204 a. The method of removing the portion of the conductive layer 228 is, for example, an etching method.

The patterned photoresist layer 230 may be removed. The method of removing the patterned photoresist layer 230 is, for example, a dry stripping method or a wet stripping method.

Referring to FIG. 2Q, a liner material layer 232 may be conformally formed on the dielectric layer 224 a, the conductive line 228 a, the doped layer 204 a, the doped layer 206 a, and the hard mask layer 208 a. The material of the liner material layer 232 is, for example, silicon oxide. The method of forming the liner material layer 232 is, for example, a CVD method or an ALD method.

A dielectric material layer 234 may be formed on the liner material layer 232. The material of the dielectric material layer 234 is, for example, silicon nitride, silicon carbonitride, silicon oxynitride, or a combination thereof. The method of forming the dielectric material layer 234 is, for example, a CVD method or an ALD method.

Referring to FIG. 2R, a portion of the dielectric material layer 234, a portion of the liner material layer 232, and the hard mask layer 208 a may be removed, thereby exposing the top surface of the doped layer 206 a and forming a dielectric layer 234 a and liner layer 232 a on the dielectric layer 224 a and the conductive line 228 a. The dielectric layer 234 a may be located on the liner layer 232 a. The liner layer 232 a may be in direct contact with the dielectric layer 224 a, the conductive line 228 a, the doped layer 204 a, and the doped layer 206 a. In some embodiments, a portion of the doped layer 206 a may be removed. The method of removing a portion of the dielectric material layer 234, a portion of the liner material layer 232, the hard mask layer 208 a, and a portion of the doped layer 206 a is, for example, a CMP method.

Referring to FIG. 2S, an opening OP3 exposing the conductive line 218 a may be formed in the dielectric layer 234 a, the liner layer 232 a, the dielectric layer 224 a, and the liner layer 222 a, and an opening OP4 exposing the conductive line 228 a may be formed in the dielectric layer 234 a and the liner layer 232 a. The method of forming the opening OP3 is, for example, removing a portion of the dielectric layer 234 a, a portion of the liner layer 232 a, a portion of the dielectric layer 224 a, and a portion of the liner layer 222 a by a lithography process and an etching process. In addition, the method of forming the opening OP4 is, for example, removing a portion of the dielectric layer 234 a and a portion of the liner layer 232 a by a lithography process and an etching process.

Referring to FIG. 2T, a conductive plug 236 and a conductive plug 238 may be respectively formed in the opening OP3 and the opening OP4. Thereby, the conductive plug 236 connected to the conductive line 218 a may be formed, and the conductive plug 238 connected to the conductive line 228 a may be formed. The material of the conductive plug 236 and the conductive plug 238 is, for example, tungsten. The conductive plug 236 and the conductive plug 238 may be electrically connected to the conductive line 218 a and the conductive line 228 a, respectively. In some embodiments, the conductive plug 236 may be in direct contact with the conductive line 218 a, and the conductive plug 238 may be in direct contact with the conductive line 228 a. The method of forming the conductive plug 236 and the conductive plug 238 is, for example, forming a conductive layer (not shown) filling the opening OP3 and the opening OP4, and then removing the conductive layer located outside the opening OP3 and the opening OP4 by a CMP method.

A conductive line 240 connected to the doped layer 206 a is formed. In addition, a conductive line 242 connected to the conductive plug 236 may be formed. Furthermore, a conductive line 244 connected to the conductive plug 238 may be formed. The conductive line 240, the conductive line 242, and the conductive line 244 may be located on the same plane, thereby facilitating the integration with the back end of line (BEOL) process. The conductive line 240, the conductive line 242, and the conductive line 244 may be electrically connected to the doped layer 206 a, the conductive plug 236, and the conductive plug 238, respectively. In some embodiments, the conductive line 240 may be in direct contact with the doped layer 206 a, the conductive line 242 may be in direct contact with the conductive plug 236, and the conductive line 244 may be in direct contact with the conductive plug 238. The material of the conductive line 240, the conductive line 242, and the conductive line 244 is, for example, aluminum, tungsten, or titanium. The method of forming the conductive line 240, the conductive line 242, and the conductive line 244 is, for example, forming a conductive layer (not shown) by a deposition process, and then patterning the conductive layer by a lithography process and an etching process.

Hereinafter, the image sensor structure 20 of the above embodiment will be described with reference to FIG. 2T. In addition, although the method for forming the image sensor structure 20 is described by taking the above method as an example, the invention is not limited thereto.

Referring to FIG. 2T, the image sensor structure 20 includes a substrate 200, a nanowire structure 210, a conductive line 218 a, a conductive line 228 a, and a conductive line 240. The nanowire structure 210 includes a doped layer 200 a, a doped layer 202 a, a doped layer 204 a, and a doped layer 206 a sequentially stacked on the substrate 200. The doped layer 200 a and the doped layer 204 a have the first conductive type (e.g., P-type). The doped layer 202 a and the doped layer 206 a have the second conductive type (e.g., N-type). The doped layer 200 a and the doped layer 202 a may form an image sensing device 246. The doped layer 202 a and the doped layer 204 a may form an image sensing device 248. The doped layer 204 a and the doped layer 206 a may form an image sensing device 250. For example, the image sensing device 246 may be an image sensing device for sensing red light, the image sensing device 248 may be an image sensing device for sensing green light, and the image sensing device 250 may be an image sensing device for sensing blue light. The image sensing device 246, the image sensing device 248, and the image sensing device 250 may be photodiodes. The doped layer 200 a may be a portion of the substrate 200. The top surface of the doped layer 200 a may be higher than the top surface of another portion of the substrate 200.

The dopant concentration (e.g., N-type dopant concentration) of the doped layer 202 a may be greater than the dopant concentration (e.g., P-type dopant concentration) of the doped layer 200 a. The dopant concentration (e.g., P-type dopant concentration) of the doped layer 204 a may be greater than the dopant concentration (e.g., N-type dopant concentration) of the doped layer 202 a. The dopant concentration (e.g., N-type dopant concentration) of the doped layer 206 a may be greater than the dopant concentration (e.g., P-type dopant concentration) of the doped layer 204 a. For example, the dopant concentration of the doped layer 200 a may be 1×10¹⁵ ions/cm³ to 5×10¹⁵ ions/cm³, the dopant concentration of the doped layer 202 a may be 1×10¹⁶ ions/cm³ to 5×10¹⁶ ions/cm³, the dopant concentration of the doped layer 204 a may be 1×10¹⁷ ions/cm³ to 5×10¹⁷ ions/cm³, and the dopant concentration of the doped layer 206 a may be 1×10¹⁸ ions/cm³ to 5×10¹⁸ ions/cm³.

The conductive line 218 a is connected to the sidewall of the doped layer 202 a. In some embodiments, the cross-sectional shape of the conductive line 218 a may be L-shaped. The conductive line 228 a is connected to the sidewall of the doped layer 204 a. In some embodiments, the cross-sectional shape of the conductive line 228 a may be L-shaped. The conductive line 240 is connected to the doped layer 206 a. The conductive line 240 may be connected to the top surface of the doped layer 206 a.

The image sensor structure 20 may further include at least one of a dielectric layer 214 a, a dielectric layer 224 a, a dielectric layer 234 a, a liner layer 212 a, a liner layer 222 a, and a liner layer 232 a. The dielectric layer 214 a is disposed on the substrate 200. The conductive line 218 a is disposed on the dielectric layer 214 a. The liner layer 212 a is disposed between the dielectric layer 214 a and the substrate 200. The dielectric layer 224 a is disposed on the dielectric layer 214 a and the conductive line 218 a. The conductive line 228 a is disposed on the dielectric layer 224 a. The liner layer 222 a is disposed between the dielectric layer 224 a and the dielectric layer 214 a. The dielectric layer 234 a is disposed on the dielectric layer 224 a and the conductive line 228 a. The liner layer 232 a is disposed between the dielectric layer 234 a and the dielectric layer 224 a.

The image sensor structure 20 may further include at least one of a conductive plug 236, a conductive plug 238, a conductive line 242, and a conductive line 244. The conductive plug 236 is connected to the conductive line 218 a. The conductive plug 238 is connected to the conductive line 228 a. The conductive line 242 is connected to the conductive plug 236. The conductive line 244 is connected to the conductive plug 238.

In addition, the material, the arrangement, the forming method, and the effect of each component in the image sensor structure 20 have been described in detail in the above embodiments and are not repeated herein.

Based on the above embodiment, in the image sensor structure 20 and the manufacturing method thereof, the nanowire structure 210 includes the doped layer 200 a, the doped layer 202 a, the doped layer 204 a, and the doped layer 206 a sequentially stacked on the substrate 200. The doped layer 200 a and the doped layer 204 a have the first conductive type, and the doped layer 202 a and the doped layer 206 a have the second conductive type. In this way, the pixel of the image sensor structure 20 can have the image sensing device 246, the image sensing device 248, and the image sensing device 250 that are vertically stacked and respectively used to sense red light, green light, and blue light, thereby effectively reducing the pixel area. In addition, since the image sensing device 246, the image sensing device 248, and the image sensing device 250 may have approximately the same top view area, the image sensor structure 20 can have a balanced energy proportion of RGB. Furthermore, the manufacturing process of the image sensor structure 20 can be integrated with the manufacturing process of the complementary metal oxide semiconductor (CMOS). Moreover, two adjacent pixels in the image sensor structure 20 can be well isolated. On the other hand, the image sensor structure 20 does not need color filters, thereby reducing the manufacturing cost and the process complexity.

In summary, in the image sensor structure and the manufacturing method thereof of the aforementioned embodiment, the nanowire structure includes a first doped layer, a second doped layer, a third doped layer, and a fourth doped layer sequentially stacked on a substrate. The first doped layer and the third doped layer have the first conductive type, and the second doped layer and the fourth doped layer have the second conductive type. Thereby, the pixel of the image sensor structure can have image sensing devices that are vertically stacked and respectively used to sense red light, green light, and blue light. Therefore, the pixel area can be effectively reduced, and the energy proportion of RGB can be balanced.

Although the invention has been described with reference to the above embodiments, it will be apparent to one of ordinary skill in the art that modifications to the described embodiments may be made without departing from the spirit of the invention. Accordingly, the scope of the invention is defined by the attached claims not by the above detailed descriptions. 

What is claimed is:
 1. An image sensor structure, comprising: a substrate; a nanowire structure comprising a first doped layer, a second doped layer, a third doped layer, and a fourth doped layer sequentially stacked on the substrate, wherein the first doped layer and the third doped layer have a first conductive type, and the second doped layer and the fourth doped layer have a second conductive type; a first conductive line connected to a sidewall of the second doped layer; a second conductive line connected to a sidewall of the third doped layer; and a third conductive line connected to the fourth doped layer.
 2. The image sensor structure according to claim 1, wherein the first doped layer is a portion of the substrate, and a top surface of the first doped layer is higher than a top surface of another portion of the substrate.
 3. The image sensor structure according to claim 1, wherein the first doped layer and the second doped layer form a first image sensing device, the second doped layer and the third doped layer form a second image sensing device, and the third doped layer and the fourth doped layer form a third image sensing device.
 4. The image sensor structure according to claim 3, wherein the first image sensing device, the second image sensing device, and the third image sensing device comprise photodiodes.
 5. The image sensor structure according to claim 1, wherein a dopant concentration of the second doped layer is greater than a dopant concentration of the first doped layer, a dopant concentration of the third doped layer is greater than the dopant concentration of the second doped layer, and a dopant concentration of the fourth doped layer is greater than the dopant concentration of the third doped layer.
 6. The image sensor structure according to claim 5, wherein the dopant concentration of the first doped layer is 1×10¹⁵ ions/cm³ to 5×10¹⁵ ions/cm³, the dopant concentration of the second doped layer is 1×10¹⁶ ions/cm³ to 5×10¹⁶ ions/cm³, the dopant concentration of the third doped layer is 1×10¹⁷ ions/cm³ to 5×10¹⁷ ions/cm³, and the dopant concentration of the fourth doped layer is 1×10¹⁸ ions/cm³ to 5×10¹⁸ ions/cm³.
 7. The image sensor structure according to claim 1, wherein the third conductive line is connected to a top surface of the fourth doped layer.
 8. The image sensor structure according to claim 1, further comprising: a first dielectric layer disposed on the substrate, wherein the first conductive line is disposed on the first dielectric layer; a second dielectric layer disposed on the first dielectric layer and the first conductive line, wherein the second conductive line is disposed on the second dielectric layer; and a third dielectric layer disposed on the second dielectric layer and the second conductive line.
 9. The image sensor structure according to claim 1, further comprising: a first conductive plug connected to the first conductive line; and a second conductive plug connected to the second conductive line.
 10. The image sensor structure according to claim 9, further comprising: a fourth conductive line connected to the first conductive plug; and a fifth conductive line is connected to the second conductive plug.
 11. An image sensor structure, comprising: a substrate; a nanowire structure comprising a first doped layer, a second doped layer, a third doped layer, and a fourth doped layer sequentially stacked on the substrate, wherein the first doped layer and the third doped layer have a first conductive type, and the second doped layer and the fourth doped layer have a second conductive type; a first conductive line connected to a sidewall of the second doped layer, wherein a cross-sectional shape of the first conductive line is L-shaped; a second conductive line connected to a sidewall of the third doped layer, wherein a cross-sectional shape of the second conductive line is L-shaped; and a third conductive line connected to the fourth doped layer.
 12. A manufacturing method of an image sensor structure, comprising: providing a substrate, wherein the substrate is a first doped material layer; sequentially forming a second doped material layer, a third doped material layer, and a fourth doped material layer on the substrate, wherein the substrate and the third doped material layer have a first conductive type, and the second doped material layer and the fourth doped material layer have a second conductive type; patterning the substrate, the second doped material layer, the third doped material layer, and the fourth doped material layer to form a nanowire structure, wherein the nanowire structure comprises a first doped layer, a second doped layer, a third doped layer, and a fourth doped layer sequentially stacked on the substrate, wherein the first doped layer and the third doped layer have the first conductive type, and the second doped layer and the fourth doped layer have the second conductive type; forming a first conductive line connected to a sidewall of the second doped layer; forming a second conductive line connected to a sidewall of the third doped layer; and forming a third conductive line connected to the fourth doped layer.
 13. The manufacturing method of the image sensor structure according to claim 12, wherein a method of forming the second doped material layer, the third doped material layer, and the fourth doped material layer comprises: performing a first epitaxial growth process to form the second doped material layer on the substrate; performing a second epitaxial growth process to form the third doped material layer on the second doped material layer; and performing a third epitaxial growth process to form the fourth doped material layer on the third doped material layer.
 14. The manufacturing method of the image sensor structure according to claim 12, wherein a method of forming the second doped material layer, the third doped material layer, and the fourth doped material layer comprises: performing a first ion implantation process on the substrate to form the second doped material layer; after performing the first ion implantation process, performing a second ion implantation process on the substrate to form the third doped material layer; and after performing the second ion implantation process, performing a third ion implantation process on the substrate to form the fourth doped material layer.
 15. The manufacturing method of the image sensor structure according to claim 14, further comprising: after performing the third ion implantation process, performing a thermal process on the substrate.
 16. The manufacturing method of the image sensor structure according to claim 12, wherein a dopant concentration of the second doped layer is greater than a dopant concentration of the first doped layer, a dopant concentration of the third doped layer is greater than the dopant concentration of the second doped layer, and a dopant concentration of the fourth doped layer is greater than the dopant concentration of the third doped layer.
 17. The manufacturing method of the image sensor structure according to claim 12, wherein a method of forming the first conductive line comprises: forming a first dielectric layer on the substrate, the first doped layer, and the second doped layer, wherein first dielectric layer exposes a portion of the sidewall of the second doped layer; conformally forming a first conductive layer on the first dielectric layer, the second doped layer, the third doped layer, and the fourth doped layer; forming a first patterned photoresist layer on the first conductive layer, the second doped layer, the third doped layer, and the fourth doped layer; reducing a height of the first patterned photoresist layer, wherein after the height of the first patterned photoresist layer is reduced, a height of a top surface of the first patterned photoresist layer is lower than a height of a top surface of the second doped layer, and the first patterned photoresist layer exposes a portion of the first conductive layer; and removing the portion of the first conductive layer exposed by the first patterned photoresist layer to form the first conductive line.
 18. The manufacturing method of the image sensor structure according to claim 17, wherein a method of forming the second conductive line comprises: forming a second dielectric layer on the first dielectric layer and the first conductive line, wherein the second dielectric layer exposes a portion of the sidewall of the third doped layer; conformally forming a second conductive layer on the second dielectric layer, the third doped layer, and the fourth doped layer; forming a second patterned photoresist layer on the second conductive layer, the third doped layer, and the fourth doped layer; reducing a height of the second patterned photoresist layer, wherein after the height of the second patterned photoresist layer is reduced, a height of a top surface of the second patterned photoresist layer is lower than a height of a top surface of the third doped layer, and the second patterned photoresist layer exposes a portion of the second conductive layer; and removing the portion of the second conductive layer exposed by the second patterned photoresist layer to form the second conductive line.
 19. The manufacturing method of the image sensor structure according to claim 12, further comprising: forming a first conductive plug connected to the first conductive line; and forming a second conductive plug connected to the second conductive line.
 20. The manufacturing method of the image sensor structure according to claim 19, further comprising: forming a fourth conductive line connected to the first conductive plug; and forming a fifth conductive line connected to the second conductive plug. 